OK, let's work through this together. We're starting with 45 and we're going to multiply it by 102, which means we add 45 to itself 102 times.
Step 1: 0 + 45 = 45
Step 2: 45 + 45 = 90
Step 3: 90 + 45 = 135
Step 4: 135 + 45 = 180
Step 5: 180 + 45 = 225
Step 6: 225 + 45 = 270
Step 7: 270 + 45 = 315
Step 8: 315 + 45 = 360
Step 9: 360 + 45 = 405
Step 10: 405 + 45 = 450
Step 11: 450 + 45 = 495
Step 12: 495 + 45 = 540
Step 13: 540 + 45 = 585
Step 14: 585 + 45 = 630
Step 15: 630 + 45 = 675
Step 16: 675 + 45 = 720
Step 17: 720 + 45 = 765
Step 18: 765 + 45 = 810
Step 19: 810 + 45 = 855
Step 20: 855 + 45 = 900
Step 21: 900 + 45 = 945
Step 22: 945 + 45 = 990
Step 23: 990 + 45 = 1035
Step 24: 1035 + 45 = 1080
Step 25: 1080 + 45 = 1125
Step 26: 1125 + 45 = 1170
Step 27: 1170 + 45 = 1215
Step 28: 1215 + 45 = 1260
Step 29: 1260 + 45 = 1305
Step 30: 1305 + 45 = 1350
Step 31: 1350 + 45 = 1395
Step 32: 1395 + 45 = 1440
Step 33: 1440 + 45 = 1485
Step 34: 1485 + 45 = 1530
Step 35: 1530 + 45 = 1575
Step 36: 1575 + 45 = 1620
Step 37: 1620 + 45 = 1665
Step 38: 1665 + 45 = 1710
Step 39: 1710 + 45 = 1755
Step 40: 1755 + 45 = 1800
Step 41: 1800 + 45 = 1845
Step 42: 1845 + 45 = 1890
Step 43: 1890 + 45 = 1935
Step 44: 1935 + 45 = 1980
Step 45: 1980 + 45 = 2025
Step 46: 2025 + 45 = 2070
Step 47: 2070 + 45 = 2115
Step 48: 2115 + 45 = 2160
Step 49: 2160 + 45 = 2205
Step 50: 2205 + 45 = 2250
Step 51: 2250 + 45 = 2295
Step 52: 2295 + 45 = 2340
Step 53: 2340 + 45 = 2385
Step 54: 2385 + 45 = 2430
Step 55: 2430 + 45 = 2475
Step 56: 2475 + 45 = 2520
Step 57: 2520 + 45 = 2565
Step 58: 2565 + 45 = 2610
Step 59: 2610 + 45 = 2655
Step 60: 2655 + 45 = 2700
Step 61: 2700 + 45 = 2745
Step 62: 2745 + 45 = 2790
Step 63: 2790 + 45 = 2835
Step 64: 2835 + 45 = 2880
Step 65: 2880 + 45 = 2925
Step 66: 2925 + 45 = 2970
Step 67: 2970 + 45 = 3015
Step 68: 3015 + 45 = 3060
Step 69: 3060 + 45 = 3105
Step 70: 3105 + 45 = 3150
Step 71: 3150 + 45 = 3195
Step 72: 3195 + 45 = 3240
Step 73: 3240 + 45 = 3285
Step 74: 3285 + 45 = 3330
Step 75: 3330 + 45 = 3375
Step 76: 3375 + 45 = 3420
Step 77: 3420 + 45 = 3465
Step 78: 3465 + 45 = 3510
Step 79: 3510 + 45 = 3555
Step 80: 3555 + 45 = 3600
Step 81: 3600 + 45 = 3645
Step 82: 3645 + 45 = 3690
Step 83: 3690 + 45 = 3735
Step 84: 3735 + 45 = 3780
Step 85: 3780 + 45 = 3825
Step 86: 3825 + 45 = 3870
Step 87: 3870 + 45 = 3915
Step 88: 3915 + 45 = 3960
Step 89: 3960 + 45 = 4005
Step 90: 4005 + 45 = 4050
Step 91: 4050 + 45 = 4095
Step 92: 4095 + 45 = 4140
Step 93: 4140 + 45 = 4185
Step 94: 4185 + 45 = 4230
Step 95: 4230 + 45 = 4275
Step 96: 4275 + 45 = 4320
Step 97: 4320 + 45 = 4365
Step 98: 4365 + 45 = 4410
Step 99: 4410 + 45 = 4455
Step 100: 4455 + 45 = 4500
Step 101: 4500 + 45 = 4545
Step 102: 4545 + 45 = 4590

So, 45*102 = 4590